Update travis-ci badge in README.md

Author: consideRatio

README.md

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 # batchspawner for Jupyterhub
 
-[![Build Status](https://img.shields.io/travis/com/jupyterhub/batchspawner?logo=travis)](https://travis-ci.org/jupyterhub/batchspawner)
+[![Build Status](https://img.shields.io/travis/com/jupyterhub/batchspawner?logo=travis)](https://travis-ci.com/jupyterhub/batchspawner)
 
 This is a custom spawner for [Jupyterhub](https://jupyterhub.readthedocs.io/) that is designed for installations on clusters using batch scheduling software.